Format: ORAL

Aluoneswi C. Mashau, Gareth P. Hempson, Caroline E.R. Lehmann, Maria S. Vorontsova, Cedrique L. Solofondranohatra, Abraham Dabengwa, Jan Hackel, Sally Archibald

1 Foundational Research and Services, South African National Biodiversity Institute (SANBI), Private Bag X101, Pretoria, 0184, South Africa. Email: c.mashau@sanbi.org.za 2 School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, Private Bag X3, Wits, 2050, South Africa 3 Tropical Diversity, Royal Botanic Garden Edinburgh, Edinburgh EH3 5LR, UK 4 School of GeoSciences, University of Edinburgh, Edinburgh EH9 3FF, UK 5 Accelerated Taxonomy, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AE, UK 6L aboratoire de Botanique, Département de Biologie et Ecologie Végétales, Faculté des Sciences, Université d'Antananarivo, Antananarivo, Madagascar 7 Kew Madagascar Conservation Centre, Antananarivo, Madagascar 8 Universität Marburg, Fachbereich Biologie, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany

Grass floral structures vary greatly but we have very little understanding of their functional significance. Due to the varied dispersal mechanisms shown by grasses, certain syndromes of floral traits would likely be associated with particular strategies for dispersal, and consequently, different environments. In particular, effective seed maturation and dispersal in fire-prone tall grasslands would require different floral trait syndromes than in short, frequently grazed ecosystems. Here we quantify floral traits of nearly 200 Poaceae species from savanna and grassland ecosystems in southern Africa and explore how their floral structures co-vary and correlate with other functional characteristics such as grass height. Using field information on the dominance disturbance regime of 163 of these grass species it was tested whether certain floral traits are more associated with fire vs grazing and mean rainfall arranged from 3231256 mm.yr-1 in the study areas. Non-metric multi-dimensional scaling (NMDS) was used to illustrate how floral traits covaried among grass species, and to group them into syndromes based on these traits. Analysis of variance (ANOVA) was used to test whether certain floral trait syndromes were more associated with fire vs grazing. We identified four clear floral trait syndromes separated largely by awn length and the presence of hooks/prickles or bristles. Long-awned species were more likely to be found in frequently burned environments and were also usually taller than species without awns. Grazer-dominated systems appear to select for two different floral trait syndromes which are no lemma awns, blunt or no callus sharpness. The study has improved our ecological and taxonomic understanding of how floral traits differ among the range of tribes in one family across African countries. It can help in understanding dispersal limitations in grasses and predicting which species are likely to flourish in particular grassland habitats.